The priority is the order in which ADRIFT goes through all of the tasks looking for a match with player input, so you must never have two general tasks with the same priority or it would get confused.If you have two tasks that match "Look at object" then ADRIFT needs to know which one to check restrictions for first, otherwise there would be no control over how the game worked and it would be full of weird bugs.

Whenever you create a new task with the same priority as an existing task, ADRIFT will change the priority of as many tasks as necessary to make room in the list for the new one while ensuring no two have the same priority.